Harvesting of wild olive trees called oleasters has been documented from the Near East (the area around ancient Palestine and Jordan) to Spain since the Neolithic or New Stone Age that started about 10,000 BC.

The tree then became domesticated, a process thought by some researchers to have started in the Near East about 6000 years ago.

Other experts, though, have offered evidence for simultaneous domestication of different olive cultivars across the Mediterranean.

Using genetic data, molecular dating, fossil records and climate modelling the researchers conclude "the western Mediterranean was not a major primary centre of domestication of the olive tree".

Instead they write, "the cradle of primary domestication of the olive tree is located in the northeastern Levant".

Central to Greek mythology

From there, the domesticated olive probably spread through the eastern Mediterranean and Cyprus, westwards to Turkey, Greece, Italy and the rest of the Mediterranean "in parallel to the expansion of civilisations and human exchanges in this part of the world", the study says.

The domesticated olive tree, Olea europaea, is central to Greek, Roman and early Christian mythology, and the olive branch remains a symbol of peace today.

The ancient Greeks believed Athena, goddess of war and wisdom, presented the Athenians with their first domesticated olive tree, from which all others sprouted.

"The importance of the cultivated olive tree in people's lives has turned this species into a symbol of ancient, sacred literature, and the origins of this crop are often subject to controversies," the paper says.

"According to our study, the maternal origin of the majority (about 90 per cent) of cultivated olives today is clearly the Near East," or roughly the modern-day Middle East, says Besnard.

"I don't think anybody will dispute that anymore."

For the study, the team sampled DNA data from 534 cultivated olive types and 1263 oleasters from 108 locations, as well as 49 trees from a sub-Saharan subspecies.

The researchers also conclude that three main branches of wild olive split from a common ancestor at least 1.5 million years ago, says Besnard.

The olive tree has been called "the tree of life" for the sustenance it provides and its non-food uses, ranging from soap to oil for lighting and sculpture.

The olive today yields some 2.4 million tonnes of oil in Europe alone, with Spain the top producer.

It is farmed as far afield as southern Africa, Australia, Japan and China.